/**
 * QUANSHI.com Inc.
 * Copyright (c) 2016-2017 All Rights Reserved.
 */
package com.quanshi.scheduler.core.utils;

import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.UnknownHostException;
import java.util.Enumeration;
import java.util.regex.Pattern;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Ip Utils
 * 
 * @author yanxiang.huang 2017-07-07 17:59:36
 */
public class IpUtils {

    private static final Logger         logger        = LoggerFactory.getLogger(IpUtils.class);

    private static final String         ANYHOST       = "0.0.0.0";

    private static final String         LOCALHOST     = "127.0.0.1";
    
    private static final String         VMHOST        = "0.1";

    public static final Pattern         IP_PATTERN    = Pattern.compile("\\d{1,3}(\\.\\d{1,3}){3,5}$");

    private static volatile InetAddress LOCAL_ADDRESS = null;

    /**
     * valid address
     * 
     * @param address
     * @return
     */
    private static boolean isValidAddress(InetAddress address) {
        if (address == null || address.isLoopbackAddress()) {
            return false;
        }
        String name = address.getHostAddress();
        return (name != null && !ANYHOST.equals(name) && !name.endsWith( VMHOST ) && !LOCALHOST.equals(name) && IP_PATTERN.matcher(name).matches());
    }

    /**
     * get first valid address
     * 
     * @return
     */
    private static InetAddress getFirstValidAddress() {
        InetAddress localAddress = null;
        try {
            localAddress = InetAddress.getLocalHost();
            if (isValidAddress(localAddress)) {
                return localAddress;
            }
        } catch (Throwable e) {
            logger.error("Failed to retriving ip address.", e);
        }
        try {
            Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
            if (interfaces != null) {
                while (interfaces.hasMoreElements()) {
                    try {
                        NetworkInterface network = interfaces.nextElement();
                        Enumeration<InetAddress> addresses = network.getInetAddresses();
                        if (addresses != null) {
                            while (addresses.hasMoreElements()) {
                                try {
                                    InetAddress address = addresses.nextElement();
                                    if (isValidAddress(address)) {
                                        return address;
                                    }
                                } catch (Throwable e) {
                                    logger.error("Failed to retriving ip address.", e);
                                }
                            }
                        }
                    } catch (Throwable e) {
                        logger.error("Failed to retriving ip address.", e);
                    }
                }
            }
        } catch (Throwable e) {
            logger.error("Failed to retriving ip address.", e);
        }
        logger.error("Could not get local host ip address, will use 127.0.0.1 instead.");
        return localAddress;
    }

    /**
     * get address
     * 
     * @return
     */
    private static InetAddress getAddress() {
        if (LOCAL_ADDRESS != null) {
            return LOCAL_ADDRESS;
        }
        InetAddress localAddress = getFirstValidAddress();
        LOCAL_ADDRESS = localAddress;
        return localAddress;
    }

    /**
     * get ip
     * 
     * @return
     */
    public static String getIp() {
        InetAddress address = getAddress();
        if (address == null) {
            return null;
        }
        return address.getHostAddress();
    }

    /**
     * get ip:port
     * 
     * @param port
     * @return
     */
    public static String getIpPort(int port) {
        String ip = getIp();
        if (ip == null) {
            return null;
        }
        return ip.concat(":").concat(String.valueOf(port));
    }

    public static void main(String[] args) throws UnknownHostException {
        System.out.println(getIp());
        System.out.println(getIpPort(8080));
    }

}
